Relationship between serum PDGF-AA and –BB and BM MSC numbers. A) Correlations between changes in serum PDGF-AA or -BB with changes in BM MSCs in the same patient. Baseline (Day 0) data for each patient were denoted as 100% and the second time points are shown as a proportionate fold-change. B) Correlations between serum PDGF-AA or -BB and circulating platelet levels in the same patient. C) The lack of correlations between serum PDGF-AA or -BB with circulating white cell counts (WCC) in the same patients. D) Trends for PDGF-AA changes over time, with initial decline after trauma followed by a gradual rise by day 7 post trauma. Left panel – raw data, right panel – data normalised to baseline (Day 0 shown as 100%). BM, bone marrow; MSC, mesenchymal stem cell; PDGF, platelet-derived growth factor.